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Discussion Starter · #1 ·
I had a computer issue on my 302 in which caused it to run lean at WOT.

I cracked the cylinder into the water jacked and blew up a hypereutectic piston. The piece of my piston appears to have hammered up the cylinder head (AFR 165s) slightly...but it's fine.

I pulled the valves for that cylinder...the intake looked fine, but when spun the exhaust valve in a drill and there was a very slight, but hardly noticeable wobble toward the valve end.

The section where the valve actually seats to the head looks undamaged, so what is the procedure for installing the new valves (I'm gonna replace them both just in case)? Pops said I can't just slap them in...he says I have to use some sort of valve grinding compound or something


Images are HERE


IDK if you can really tell, but the damage is nowhere near the groove where the valve sits. I don't think the little damage there will be an issue.
 

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New valve should be lapped in to make sure it contacts the seat all the way around. Seat could maybe be checked for runout, but I'm not seeing any damage so it's probably in good shape.
 

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Discussion Starter · #3 ·
New valve should be lapped in to make sure it contacts the seat all the way around. Seat could maybe be checked for runout, but I'm not seeing any damage so it's probably in good shape.
I'm an IT guy, so I'm trying to get the terminology right here.

I guess the seat means the groove that is tongue/groove lip is...or its the entire angled portion?

Either way, there was not a scratch in that area...not a single blemish


What's the procedure for lapping valves and what should I buy?
 

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To lap the valves you go to the parts store, buy some lapping compound and a stick with a suction cup on it. (really). Put a light coating of lapping compound on the valve, stick the stick on the face of the valve, slide it in the head and start twisting the valve with light pressure. You're twisting it back and forth between your hands and every now and then stop and rotate the valve 90 degrees or so. After a few minutes remove the valve, take some brake clean, clean off the valve and valve seat. The valve and seat are shining to start with, but when you lap them to create the seat, you will create a very thin gray line around the valve and seat. If the gray line has gaps or is not even on the valve or seat, lap some more. If you go more than about 10 minutes and can't get an even line around the valve and seat something is wrong. One thing you'll have to really scrutinize is whether the bent valve egg shaped or mushroomed the seat. I doubt it, but I have seen one instance where the valve seats got hammered up into the head and were cocked slightly. Had to machine them out and replace.
 

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Sorry, I go on autopilot sometimes. What droopie wrote is dead on. If it shows areas of not being lapped in, the seat will have to be re-cut.

Wonder if AFR does 3 or 5 angle valve jobs?
 

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Discussion Starter · #6 ·
Sorry, I go on autopilot sometimes. What droopie wrote is dead on. If it shows areas of not being lapped in, the seat will have to be re-cut.

Wonder if AFR does 3 or 5 angle valve jobs?
According to the site for the heads, 5 Angle.

Does it matter?
 

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Only if it needs the seat to be cut. If the valve laps in nice and evenly, then you're good to go.
 
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